The Asynchronous Transfer Mode (ATM) standard allows interoperability of information between associated systems in a communication network. Using ATM, variable-length packets are segmented into fixed-length cells and sent to a destination, where the cells are reassembled into packets. Because they are a fixed length, the cells may be sent in a predictable manner through the network, and the associated switches and transportation systems are able to achieve high-speed and flexible communications.
If an ATM switch receives a stream of ATM cells over a high-bandwidth communication link, such as an OC-3, and those cells are to be sent to another ATM switch with which the first ATM switch may only communicate using multiple lower bandwidth communication links, such as T-1 lines, a process called inverse multiplexing is sometimes used to send the cells to the second ATM switch more quickly than would otherwise be possible. This inverse multiplexing process involves the first ATM switch sending cells for some packets on one communication link and cells for other packets on other communication links. The second ATM switch then resynchronizes the packets after receiving the cells over the different communication links. One example of this inverse multiplexing process is described in U.S. Pat. No. 6,134,246 issued to Cai, et al., which is hereby incorporated by reference.
Conventional ATM switches, as well as other types of packet switches, are thus able to provide data to other packet switches at a higher rate than a single communication link connecting them would otherwise allow. However, each of these packet switches has a rated capacity that limits the speed with which the packet switch is able to switch an incoming stream of packets or cells before they are sent to another packet switch. In order to increase the capacity of one of these switches, typically the backplane is redesigned, and application and switch cards within the switch are replaced with cards that have an increased capacity for switching. However, this approach to increasing switch capacity is not always possible and, when it is possible, may be relatively expensive.
Therefore, there is a need in the art for an improved packet switch that is capable of switching packets at higher data rates without prohibitive costs. In particular, there is a need for a packet switch that is able to switch packets at a higher data rate than the packet switch's rated capacity without redesigning the backplane or replacing existing cards with higher-capacity cards.